The charging circuit charges the batteries when mains power is used to supply the amplifiers. The top section shows the 7812 IC which powers the relays that switch power over when the mains switch on the front of the amp is thrown. The lower 2 duplicate sections are to charge the batteries.
The charging circuit will use 2N3055’s to provide the current capability but these have not been added yet as they need to be attached to heatsinks and the pillar drill from Axminster has not turned up yet.
It may be that the 3 ICs shown will need heatsinks also. I could work out whether they need them or not but that takes time and I really want to keep the momemtum of the build going. Plus the currents drawn are not that high and these components are relatively inexpensive so burning one up to find out will not be a problem.
The vero board used is a very expensive type but I had it lying around. In production models plain vero board will be used (no copper tracks) and that will bring the cost down. There is no point in using air-wiring here and the time it takes far outweighs the cost of even the expensive glass-fibre vero board.